The results of 373 infrainguinal bypass grafts, in a single centre, between 1980 and 1988 are reviewed. One hundred and thirty in situ vein (ISV), 47 reversed saphenous vein (RSV), 118 polytetrafluoroethylene (PTFE) and 78 human umbilical vein (HUV) grafts were used. The indications for surgery were disabling claudication in 25 per cent of patients and limb salvage in 75 per cent. In 36 per cent of operations the distal anastomosis was above the knee and in 64 per cent it was below the knee. Overall 5-year patency rates and limb salvage rates respectively were, for ISV (41 and 69 per cent), RSV (62 and 90 per cent), PTFE (31 and 67 per cent) and HUV (29 and 59 per cent). There was no significant difference in patency among these grafts at the above-knee level, but significant differences between vein and prosthetic grafts were evident below the knee (P less than 0.001). Using a proportional hazards model the three factors that consistently correlated with late graft patency were graft type (P less than 0.001), site of distal anastomosis (P less than 0.001) and distal run-off (P less than 0.001). Overall, the results suggest that prosthetic grafts are a suitable alternative to autogenous vein when the distal anastomosis is above the knee, but vein should always be used, if available, below the knee joint.
Summary Angiotensin II (AT-IT) has been used to target regionally-administered cytotoxic microspheres in patients with intrahepatic tumours. The optimisation of vasoconstrictor targeting requires a knowledge of the blood flow changes induced by agents such as AT-IT. We therefore assessed duplex/colour Doppler sonography (DCDS) as a means of evaluating the effects of AT-TI infusion on hepatic arterial blood flow (HABF) and arterial resistance in patients with intrahepatic tumours.HABF was measured continuously in nine patients using DCDS before, during and after an infusion of AT-II (15 MethodsNine patients (age range 48-69 years) with colorectal liver metastases were studied. All patients had an indwelling hepatic artery catheter with a subcutaneous injection port (Portacath, Pharmacia, or Infusaid, Shiley Infusaid Inc.) for administration of regional chemotherapy. The effects of an angiotensin II infusion (given as 15 micrograms in 3 ml of normal saline over 90 s on hepatic arterial blood flow (HABF) were measured using DCDS (Diasonics Spectra, Diansonics Sonotron Ltd, Bedford, UK) in conscious, fasted patients. The technique for measuring HABF, which was calculated as the product of the time average velocity and arterial cross-sectional area, has been described previously (Leen et al., 1991). The Diasonics Spectra scanner consists of duplex and colour Doppler facilities and a 3.5 MHz convex linear array probe was used. In the Doppler mode ultrasound waves were emitted and received by a single probe at a frequency of 3 MHz with a repitition frequency of 3.7 MHz.A transverse scan was made at the epigastrium to locate the common hepatic artery in its longitudinal axis. The Doppler cursor was placed over the lumen of the artery segment as near to the origin as possible, at the point where it first became horizontally straight. Spectral analysis was performed using fast Fourier transformation and the Doppler shift signal was displayed on the monitor. The system was equipped with software to compute the time average velocity from the spectral display automatically following placement of the calipers at the start and end of four cardiac cycles. This was done every 30 s while 15 micrograms of AT-II in 3 ml saline was infused through the hepatic arterial catheter over a period of 90 s.The cross-sectional area of the artery was measured by mapping the perimeter of the vessel lumen with the 'tracker ball'. As it was not possible to do this simultaneously with blood velocity measurement during the AT-II infusion, a single value for the area was used to calculate flow rates for a given patient. This was the mean of four individual measurements taken at the same location in the vessel at random phases of the cardiac cycle. In five patients, arterial cross-sectional area was measured every 30 s during a separate AT-II infusion. No systemic change in area was observed during the infusion, and the mean coefficient of variation of the area was only 3.9%, justifying the assumption that it could be regarded as constant.
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